| Current Conditions | ||
| Temp |  | 2.1 C |
| RH | | 70 % |
| Wind | | SW 0 mph |
| Road | | Open |
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Hawaiian Islands Synoptic Discussion and Guidance 353 FXHW60 PHFO 101723 AAA AFDHFO AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE HONOLULU HI 715 AM HST MON MAR 10 2014 .UPDATE... CLOUDY PERIODS WITH LOCALLY HEAVY RAINFALL POSSIBLE THIS AFTERNOON FOR MOST OF THE WINDWARD BIG ISLAND...AND MOST BIG ISLAND SLOPES AND LEEWARD AREAS. && .SYNOPSIS... TRADE WINDS WILL CONTINUE ACROSS THE MAIN HAWAIIAN ISLANDS THROUGH MOST OF THE FORECAST PERIOD AS HIGH PRESSURE BECOMES DOMINANT TO OUR NORTH. CLOUDS AND SHOWERS WILL FAVOR WINDWARD AND MAUKA AREAS...EXCEPT FOR POSSIBLE HEAVY SHOWERS ALONG THE BIG ISLAND SLOPES THIS AFTERNOON. A DIGGING UPPER TROUGH EAST OF THE ISLANDS MAY ENHANCE SHOWERS TODAY THROUGH TUESDAY. A COLD FRONT WILL REACH THE ISLANDS FRIDAY...USHERING IN STRONG AND GUSTY TRADE WINDS IN ITS WAKE FOR THE WEEKEND. && .DISCUSSION... A 1028 MB HIGH NEAR 37N136W...FAR NORTHEAST OF THE MAIN HAWAIIAN ISLANDS...HAS AN ASSOCIATED RIDGE EXTENDING SOUTHWEST THROUGH 27N155W AND 23N172W. THE PRESSURE GRADIENT BETWEEN THIS RIDGE AND EQUATORIAL LOW PRESSURE IS SUFFICIENTLY STEEP TO SUPPORT MODERATE EASTERLY TRADE WINDS ACROSS LOCAL WATERS THIS MORNING. SATELLITE LOOP SHOWS ABUNDANT LOW CLOUDS FAVORING WINDWARD AND MAUKA AREAS...WITH RADAR SHOWING MODERATE TO HEAVY SHOWERS ACROSS WINDWARD AND SOUTHEAST SECTIONS OF THE BIG ISLAND. MODERATE SHOWERS WERE NOTED ACROSS MANY WINDWARD SECTIONS OF THE SMALLER ISLANDS. WE EXPECT A CONTINUED PATTERN OF LOW CLOUDS AND SHOWERS FAVORING WINDWARD AND MAUKA AREAS THROUGH THE WEEK. UPPER TROUGHING EAST OF THE ISLANDS IS EXPECTED TO INTENSIFY INTO MIDWEEK AS THE TROUGH MOVES AWAY. MOST ASSOCIATED ADVERSE EFFECTS WILL BE EAST OF THE ISLANDS...BUT TRADE SHOWERS COULD BE ENHANCED TODAY THROUGH TUESDAY. WITH 1.5 TO 2.5 INCH PER HOUR RAINFALL RATES NOTED OVERNIGHT AT WINDWARD BIG ISLAND GAGES...THIS INTENSIFYING UPPER TROUGH MAY ALREADY BE HAVING AN EFFECT ON LOCAL WEATHER. MODELS SHOW THE HIGH TO OUR NORTHEAST WILL MOVE AWAY OVER THE NEXT 36 HOURS WHILE ANOTHER HIGH NOSES IN FROM THE WEST. IN THE SHORT INTERVAL...THE RIDGE WILL BE WEAKER TO OUR NORTH AND TRADE WINDS ACROSS LOCAL WATERS WILL DECREASE DURING THE DAY TODAY. BY TUESDAY...THE SECOND HIGH SHOULD BE IN PLACE TO OUR NORTH AND TRADE WINDS SHOULD BE STRONGER IN RESPONSE. WIND DIRECTION WILL BE NORTHEASTERLY INSTEAD OF EASTERLY AND TRADE FLOW SHOULD CONTINUE UNINTERRUPTED THROUGH FRIDAY. BY LATE FRIDAY...MODELS SHOW A COLD FRONT APPROACHING FROM THE NORTHWEST WILL REACH KAUAI. THE ASSOCIATED COL IN LOW LEVEL FLOW WILL BE NORTH OF THE ISLANDS...SO WINDS ACROSS LOCAL WATERS WILL REMAIN TRADES AS THE FRONT APPROACHES INSTEAD OF VEERING TO SOUTHERLIES. LATEST MODEL RUNS SHOW THIS FRONT WILL REACH THE BIG ISLAND BY LATE SATURDAY AND THE FOLLOWING HIGH WILL USHER IN STRONG AND GUSTY NORTH NORTHEAST WINDS IN ITS WAKE. IT IS TOO EARLY TO TELL HOW MUCH RAINFALL THERE WILL BE AS THE FRONT PASSES BY. && .AVIATION... EXPECT PREDOMINANTLY VFR CONDITIONS AT ALL TERMINALS OVER THE NEXT 24 HOURS. HOWEVER...AIRMET SIERRA FOR MVFR CEILINGS OVER WINDWARD AND MOUNTAIN AREAS WILL LIKELY REMAIN IN EFFECT THROUGH THE MORNING HOURS. AFTERNOON SEA BREEZES ARE EXPECTED...ESPECIALLY ACROSS LEEWARD SECTIONS OF MAUI AND THE BIG ISLAND. THE PASSAGE OF AN UPPER LEVEL TROUGH JUST TO THE EAST OF THE ISLANDS COULD NECESSITATE AN AIRMET FOR UPPER LEVEL TURBULENCE FOR THE STATE THIS AFTERNOON. && .MARINE... A MODERATE NW SWELL WILL BUILD ON TUESDAY...PEAK ON WEDNESDAY...THEN LOWER SLOWLY ON THURSDAY. A SLIGHTLY LARGER NW SWELL IS EXPECTED TO BUILD THURSDAY NIGHT...WITH SURF EXPECTED TO REACH ADVISORY LEVELS BY FRIDAY ON SOME OF THE N AND W FACING SHORES. TRADE WINDS MAY REACH SMALL CRAFT ADVISORY STRENGTH...AT LEAST ACROSS THE TYPICALLY WINDY ZONES...BY MIDWEEK. WINDS WILL STRENGTHEN FURTHER THIS WEEKEND DUE TO A STRONG HIGH NW OF THE STATE BEHIND A PASSING FRONT. BY THEN...SMALL CRAFT ADVISORY CONDITIONS WILL LIKELY EXIST IN ALL COASTAL WATERS...WITH THE POSSIBILITY OF GALE WARNINGS IN THE CHANNELS. && .HFO WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION/MARINE...POWELL AVIATION...BEDAL Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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